The invention relates to optical fibers having large numerical apertures. The fibers consist of multicomponent glasses. The optical fibers may be of the so-called multimode, stepped index type or of the graded index type.
Optical fibres having a large numerical aperture, i.e. approximately 0.30 or larger, usually comprise at least in the core glass germanium dioxide. Germanium dioxide is a comparatively expensive component. In addition, such a fiber is sensitive to high energy radiation due to the comparatively high germanium content. This results in an increase in the attenuation of an irradiated fiber. The increased attenuation only partly disappears after the irradiation ceases.